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Search for "milling" in Full Text gives 91 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of 2,2-difluoro-1,3-diketone and 2,2-difluoro-1,3-ketoester derivatives using fluorine gas
Beilstein J. Org. Chem. 2024, 20, 460–469, doi:10.3762/bjoc.20.41
- , but the second fluorination step occurs only after reaction for several days. In the solid phase, mechanical milling of the diketone substrate with solid Selectfluor in the presence of sodium carbonate [13][14], and reaction of ketones with a strong base and an N–F reagent give rise to the
Green and sustainable approaches for the Friedel–Crafts reaction between aldehydes and indoles
Beilstein J. Org. Chem. 2024, 20, 379–426, doi:10.3762/bjoc.20.36
- development of greener synthetic technologies, like photocatalysis, organocatalysis, the use of nanocatalysts, microwave irradiation, ball milling, continuous flow, and many more. Thus, in this review, we summarize the medicinal properties of BIMs and the developed BIM synthetic protocols, utilizing the
- ]. In 2021, this methodology was reiterated by Wu et al., who conducted the reaction in the exact same conditions, utilizing the ball milling technique, instead of solid grinding, which slightly reduced reaction times and the catalyst loading necessary from 500 mg to 300 mg [119]. The substrate scope
Clauson–Kaas pyrrole synthesis using diverse catalysts: a transition from conventional to greener approach
Beilstein J. Org. Chem. 2023, 19, 928–955, doi:10.3762/bjoc.19.71
- to reduce energy consumption and the carbon footprint. The traditional heating techniques used to synthesize compounds are being replaced by contemporary green alternative energy systems, such as photocatalysis, microwave irradiation, ultrasonic irradiation, grinding, and ball milling processes
Mechanochemical solid state synthesis of copper(I)/NHC complexes with K3PO4
Beilstein J. Org. Chem. 2023, 19, 440–447, doi:10.3762/bjoc.19.34
- milling the ligand precursor 1 with metallic copper powder in air [45]. Another mechanochemical pathway was published using K2CO3 as a base and copper(I) chloride [46][47]. This latter procedure is practical, avoids the use of solvents, and relies on an abundant and cheap base. We have recently disclosed
- during the milling process lead to agglutination of the remaining solids and therefore insufficient homogenization of the reaction mixture. This gave a mixture of compounds, in which the envisaged complex 5 could not be identified. A different approach was made using sodium hydride as a base (Table 1
- indicated the presence of 5, but also of unwanted side-products that could not be identified. Purification of 5 from this complex mixture turned out not to be feasible. Further modifications of the milling conditions did not lead to the elimination of these side-products, therefore the experiments with NaH
Dissecting Mechanochemistry III
Beilstein J. Org. Chem. 2022, 18, 1454–1456, doi:10.3762/bjoc.18.150
- , Colombia 10.3762/bjoc.18.150 In the past ten years, the use of mechanochemical techniques (e.g., grinding, milling, extrusion, pulsed ultrasonication, resonant acoustic mixing, etc.) have widespread in the field of organic chemistry, enabling the development of new and more sustainable protocols for
- Margetić used dibrominated polycyclic imides as substrates to generate reactive alkenes, which could be trapped in situ by several dienes through Diels−Alder cycloadditions by ball milling (Scheme 3) [7]. Further, Moores and co-workers synthesized phosphorus-bridged heptazine-based carbon nitrides (g-h-PCN
Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides
Beilstein J. Org. Chem. 2022, 18, 1416–1423, doi:10.3762/bjoc.18.147
- , University of Illinois at Chicago, Chicago, Illinois 60612, United States 10.3762/bjoc.18.147 Abstract In this paper, we report the mechanochemical synthesis of unsymmetrical salens using grinding and ball milling technologies, respectively, both of which were afforded in good yield. The chelating effect of
- monohydrochlorides and salicylaldehydes (blue in Scheme 2) took 1 hour for reaction completion. After adding another salicylaldehyde (red in Scheme 2), Et3N, and methanol, the second reaction step was completed in an additional hour, monitored by TLC. Yields of unsymmetrical salens using grinding and ball milling
- were summarized in Table 1. We were surprised that the overall yield from ball milling was lower than the overall yield from grinding, suggesting a higher revolution per minute (RPM) could be necessary to increase the reaction yield using ball milling. It is assumed that the forces are not equivalent
Polymer and small molecule mechanochemistry: closer than ever
Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128
- (mechanochemistry) can be accomplished through various experimental strategies. Among them, ultrasonication of polymeric matrices and ball milling of reaction partners have become the two leading approaches to carry out polymer and small molecule mechanochemistry, respectively. Often, the methodological differences
- molecule mechanochemistry sometimes overlap, evidencing the connection between both approaches. Keywords: ball milling; mechanochemistry; mechanophore; polymer; pulsed ultrasonication; Introduction In the past two decades, the growth in popularity of mechanochemistry has been unmistakable. During this
- (mechanophores) embedded along the polymer chains (Figure 1a) [1][2][3][4]. This is mostly accomplished through pulsed ultrasonication, and to a lesser extent by single-molecule force spectroscopy techniques [5][6]. The second approach habitually makes use of ball milling techniques to bring together small
From amines to (form)amides: a simple and successful mechanochemical approach
Beilstein J. Org. Chem. 2022, 18, 1210–1216, doi:10.3762/bjoc.18.126
- ]. In general, mechanochemistry refers to studying solid-state chemical changes promoted by external mechanical energy, such as grinding or milling. A deeper understanding of its mechanistic aspects laid the basis for further growth in this topic, opening new routes to more efficient mechanochemical
- ][50][51][52][53][54], no systematic report of N-formylation and N-acetylation by ball milling has been reported yet. Here, we describe two complementary procedures to prepare formamides and acetamides, applied to primary and secondary aromatic and aliphatic amines. The methodologies directly involve
- HCO2H derivatives and CH3CO2H and two activating agents for promoting amide coupling. Results and Discussion We started our investigation by reacting p-methoxyaniline (1.0 mmol) with ammonium formate (3.0 mmol) (Table 1, entry 1) in a zirconia jar in the presence of one milling ball of the same material
Mechanochemical bottom-up synthesis of phosphorus-linked, heptazine-based carbon nitrides using sodium phosphide
Beilstein J. Org. Chem. 2022, 18, 1203–1209, doi:10.3762/bjoc.18.125
- functional theory (DFT) and electron energy loss spectroscopy (EELS). Compared to traditional furnace-based techniques, the presented method utilizes milder conditions, as well as shorter reaction times. Both samples of g-h-PCN directly after milling and aging and after an hour of annealing at 300 °C (g-h
- broad Bragg reflections at 2θ = 16° and 28°. This suggests a high thermal stability of the g-h-PCN structure, being formed during the mild milling and aging conditions, with no need for annealing. X-ray photoelectron spectroscopy (XPS) To gain insight into the atomic speciation within the structure and
- well as a peak centered on 292.1 eV due to charging effects [39]. The presence of C=N bonds established by XPS indicates that the heptazine structure was preserved during milling and aging with Na3P. Nitrogen 1s focused scans of g-h-PCN showed a 62% to 38% ratio of pyridinic to pyridonic-N type
Derivatives of benzo-1,4-thiazine-3-carboxylic acid and the corresponding amino acid conjugates
Beilstein J. Org. Chem. 2022, 18, 1195–1202, doi:10.3762/bjoc.18.124
- . Several attempts were made to combine the benzothiazine motif with amino acid methyl esters (Scheme 4) using coupling agents (EDC, COMU, T3P®, etc.) or through acid chloride (SOCl2 and (COCl)2) in a flask with stirring or under ball-milling conditions. However, we were unable to isolate the desired amides
Automated grindstone chemistry: a simple and facile way for PEG-assisted stoichiometry-controlled halogenation of phenols and anilines using N-halosuccinimides
Beilstein J. Org. Chem. 2022, 18, 999–1008, doi:10.3762/bjoc.18.100
- mechanical grinding or milling, has garnered massive interest among chemists owing to its green attributes like solvent-free, clean, atom economic, and time-efficient, and has been identified by the IUPAC as one of 10 world-changing technologies [47]. While milling has received more focus, the simpler form
- requires the use of a solid acid catalyst [52], apart from the use of high-cost, high-end milling equipment which limits to laboratory scale only. Therefore, developing an operationally simple, environmentally benign protocol, potentially useful for the batch-scale synthesis of aryl halides is highly
- of the solid acid catalyst and the cost of high-end milling instruments are additional considerations for that method [52]. Conclusion In conclusion, we have developed a facile and sustainable mechanochemical route for the catalyst-free halogenation of phenol and aniline derivatives using N
Palladium-catalyzed solid-state borylation of aryl halides using mechanochemistry
Beilstein J. Org. Chem. 2022, 18, 855–862, doi:10.3762/bjoc.18.86
- , Japan 10.3762/bjoc.18.86 Abstract This study describes the solid-state palladium-catalyzed cross-coupling between aryl halides and bis(pinacolato)diboron using ball milling. The reactions were completed within 10 min for most aryl halides to afford a variety of synthetically useful arylboronates in
- , mechanochemical synthesis using ball milling has attracted considerable attention as an efficient solvent-free synthetic technique [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Notably, the strong mechanical agitation provided by ball milling enables efficient solid-state organic
- ). The reactions were conducted in a Retch MM400 ball mill in a stainless-steel milling jar (1.5 mL) at 30 Hz using one stainless-steel ball (diameter: 5 mm) for 10 min. We used a commercially available temperature-controllable heat gun that was placed directly above the ball-milling jar to control the
Complementarity of solution and solid state mechanochemical reaction conditions demonstrated by 1,2-debromination of tricyclic imides
Beilstein J. Org. Chem. 2022, 18, 746–753, doi:10.3762/bjoc.18.75
- was replaced by the Zn/Cu couple which was prepared without any metal activation by in situ ball milling of zinc and copper dusts. The advantage of the ball milling process is that the whole procedure is operationally very simplified. The reactive alkene generated was trapped in situ by several dienes
- and the respective Diels−Alder cycloadducts were obtained. It was demonstrated that mechanochemical milling offers complementary conditions to solution (thermal) reaction by allowing chemical transformations to proceed which were not possible in solution and vice versa. Keywords: ball milling
- usual procedure from Zn and silver acetate. Several simplifications of the Zn/Ag couple preparation were tested and showed that simple milling with Zn dust and Ag dust or wire can be also applied (Table 1, entries 5–8) [21]. Further improvement in the procedure was the replacement of the Ag dust with Cu
Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies
Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70
- in the fixed-bed material that interact with the oscillating electromagnetic field. Recently, Rebrov and co-workers disclosed the direct amide formation of a carboxylic acid and anilline using high energy ball milling to prepare the sulfated TiO2 (50 wt %)/NiFe2O4 (50 wt %) catalyst that serves as
Mechanochemical halogenation of unsymmetrically substituted azobenzenes
Beilstein J. Org. Chem. 2022, 18, 680–687, doi:10.3762/bjoc.18.69
- application of solid-state methods [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46], particularly ball milling [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46], which has proven to be an environmentally friendly and powerful
- alternative to conventional solvent-based protocols, offering unique advantages in terms of sustainability, reaction times, yields, reactant solubility, selectivity, and chemical reactivity. Although ball milling methods are widely used for the synthesis of various classes of compounds [26][27][28][29][30][31
- -halosuccinimide (NXS, X = Br, I) as halogen source [47]. Two years later in 2017, Eslami's group applied a ball-milling method to synthesize aryl bromides and α-bromoketones with N-bromosuccinimide (NBS) and MCM-41-SO3H catalyst and no liquid additives [48]. In 2018, Wang and co-workers developed the ball-milling
DDQ in mechanochemical C–N coupling reactions
Beilstein J. Org. Chem. 2022, 18, 639–646, doi:10.3762/bjoc.18.64
- -Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is a commonly known oxidant. Herein, we report that DDQ can be used to synthesize 1,2-disubstituted benzimidazoles and quinazolin-4(3H)-ones via the intra- and intermolecular C–N coupling reaction under solvent-free mechanochemical (ball milling) conditions. In
- toward the synthesis of 1,2-disubstituted benzimidazoles [39] under mechanochemical (ball milling) conditions (Figure 1a). In addition, the one-pot coupling of 2-aminobenzamides with aryl/alkyl aldehydes in the presence of DDQ resulted in substituted quinazolin-4(3H)-one [40] derivatives (Figure 1b
- operating milling frequency from 21 to 16 Hz (Supporting Information File 1, Table S1, entry 9). On the other hand, the yield of product 5a was unaffected by increasing the operating frequency from 21 Hz to 25 Hz (Supporting Information File 1, Table S1, entry 8). 1,2-Disubstituted benzimidazoles are
Menadione: a platform and a target to valuable compounds synthesis
Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43
Multi-faceted reactivity of N-fluorobenzenesulfonimide (NFSI) under mechanochemical conditions: fluorination, fluorodemethylation, sulfonylation, and amidation reactions
Beilstein J. Org. Chem. 2022, 18, 182–189, doi:10.3762/bjoc.18.20
- techniques, in this work we studied the reactivity of N-fluorobenzenesulfonimide (NFSI) by ball milling. We corroborated that, by mechanochemistry, NFSI can engage in a variety of reactions such as fluorinations, fluorodemethylations, sulfonylations, and amidations. In comparison to the protocols reported in
- ; sulfonylation; Introduction Mechanosynthesis of organic molecules and materials using mechanochemical techniques such as ball milling, extrusion, grinding, etc. [1][2][3] have enabled the development of known and new chemical transformations in a more sustainable fashion [4]. Commonly, mechanochemical
- reactions by ball milling involve the mechanical treatment of at least one solid reagent in the presence of other solid, liquid or gaseous reaction partners or additives [5][6]. Due to the particular reaction conditions in which mechanochemical reactions by milling are carried out, reagents need to exhibit
N-Sulfinylpyrrolidine-containing ureas and thioureas as bifunctional organocatalysts
Beilstein J. Org. Chem. 2021, 17, 2629–2641, doi:10.3762/bjoc.17.176
- influence on the catalytic reactions. Under ball-milling conditions, the Michael adducts were obtained in good yields but with slightly lower enantiomeric purities than in solution. DFT calculations elucidated its mode of action and confirmed a dual activation mode, which combines enamine activation of
- organocatalytic transformations were successfully performed under solvent-free ball-milling conditions [30][31]. In this context, we describe the synthesis of new pyrrolidine appended sulfinylurea and thiourea organocatalysts and their assessment in Michael additions of aldehydes to nitroalkenes. Furthermore, we
- )benzene (7b). Hexanal (6b) reacted successfully with 4-fluoro-β-nitrostyrene (7c) and gave product 8d under all conditions tested (in solution, solvent-free, and ball-milling conditions, vide infra). Again, small amounts of catalyst (S,R)-C2 gave the best chemical yield. Catalyst (S,R)-C2 (3 mol %) in
A straightforward conversion of 1,4-quinones into polycyclic pyrazoles via [3 + 2]-cycloaddition with fluorinated nitrile imines
Beilstein J. Org. Chem. 2021, 17, 1509–1517, doi:10.3762/bjoc.17.108
- inorganic bases, such as Et3N, K2CO3, and DBU. Along with the “traditional” reaction performed in solution, a mechanochemical approach using ball milling was also tested. The obtained results are collected and compared in Table 1. They show that the best results were achieved using dry THF as a solvent and
Synthetic accesses to biguanide compounds
Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82
- . screened various conditions for the addition of TMG to different alkyl- and arylcarbodiimides [80]. In particular, the authors compared different approaches such as classical thermic conditions, microwave irradiation with or without Y(OTf)3, high-speed vibrational milling using stainless steel balls, high
Application of the Meerwein reaction of 1,4-benzoquinone to a metal-free synthesis of benzofuropyridine analogues
Beilstein J. Org. Chem. 2021, 17, 977–982, doi:10.3762/bjoc.17.79
- nitrochromenobenzofuropyridine 21 was achieved after treatment of 16 with nitrostyrene in the presence of DABCO applying our previously reported ball milling procedure [40]. The synthesis of 22 was performed using the Perkin reaction [41]. The reaction of 16 with propionic anhydride and the corresponding sodium salt in the
Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate
Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211
- reactants throughout the solid mixture under ball-milling conditions. A weak association of bulky substrates and/or their corresponding products with the CD cavities under ball-milling conditions improved the mobility of the partners in the solid state. The reaction reactivity and selectivity were then
- constituting the reaction mixture on the reactivity for the synthesis of β-CDMts under ball-milling conditions. Additionally, in the presence of a base such as KOH, we show that the chemoselectivity of the reaction is significantly altered in favor of the β-CD product mono-substituted on the primary face, thus
- different milling times. As can be seen from Figure 1, the powder particles experience comminution and decrease in size over time and after grinding for 10 min, β-CD displays microsized particles (Figure 1c). Longer grinding times led to particles with sizes below 300 nm in diameter (Figure 1d and Figure 1e
Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors
Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202
The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY
Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188
- phenylboronic acid (PBA)-functionalized boron dipyrromethene (BODIPY) applying the ball milling approach. The ball milling formation of boron esters between PBA BODIPY and dextran proved to be more efficient in terms of reaction time, amount of reactants, and labelling degree compared to the corresponding
- biocompatibility while remaining fluorescent. Keywords: ball milling; boronic ester; dextran; bodipy; nanoparticles; Introduction In the last few decades, mechanochemistry has gathered a great deal of attention and a lot of efforts have been focused on its use in organic synthesis, catalysis, biotransformation
- evident with the development of atomized ball milling technologies, which allow for a better reproducibility and control of reaction parameters over traditional mortar or pestle [4][6]. Mechanochemical syntheses are not just a means for cleaner, safer, higher yielding, and more sustainable chemical
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